Major glycoproteins in carp CNS myelin: homology to P0 protein with HNK-1/L2 carbohydrate epitope.

We studied the myelin protein profiles of carp from a phylogenetic point of view. The carp central nerve myelin contained two reactive bands, 28 and 25 kDa, demonstrated with anti-bovine P0 antibody. Their molecular weights are slightly different from those of two positive bands found in carp peripheral myelin. The N-terminal amino acid sequences of these four positive bands were identical to one another and showed high homology with those of mammalian P0 protein, suggesting that carp central myelin contains the P0-like protein. Lectin binding analysis revealed that carbohydrate structure of the P0-like proteins in carp central myelin is similar to those in peripheral myelin of carp and other vertebrates. Further, the carp P0-like glycoproteins, like the P0 proteins of other vertebrates, reacted with antibodies that recognize the HNK-1/L2 carbohydrate epitope. We conclude that the major structural glycoprotein in central myelin of the carp is homologous to P0 protein in peripheral myelin of other higher classes of vertebrates.